When revalidating a dentry, if the inode wasn't known to be a dfs
entry when the dentry was instantiated, such as when created via
->readdir(), the DCACHE_NEED_AUTOMOUNT flag needs to be set on the
dentry in ->d_revalidate().
The false return from cifs_d_revalidate(), due to the inode now
being marked with the S_AUTOMOUNT flag, might not invalidate the
dentry if there is a concurrent unlazy path walk. This is because
the dentry reference count will be at least 2 in this case causing
d_invalidate() to return EBUSY. So the asumption that the dentry
will be discarded then correctly instantiated via ->lookup() might
not hold.
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Cc: Steve French <smfrench@xxxxxxxxx>
Cc: linux-cifs@xxxxxxxxxxxxxxx
---
fs/cifs/dir.c | 17 ++++++++++++-----
1 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index d172c8e..ec4e9a2 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -668,12 +668,19 @@ cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
return 0;
else {
/*
- * Forcibly invalidate automounting directory inodes
- * (remote DFS directories) so to have them
- * instantiated again for automount
+ * If the inode wasn't known to be a dfs entry when
+ * the dentry was instantiated, such as when created
+ * via ->readdir(), it needs to be set now since the
+ * attributes will have been updated by
+ * cifs_revalidate_dentry().
*/
- if (IS_AUTOMOUNT(direntry->d_inode))
- return 0;
+ if (IS_AUTOMOUNT(direntry->d_inode) &&
+ !(direntry->d_flags & DCACHE_NEED_AUTOMOUNT)) {
+ spin_lock(&direntry->d_lock);
+ direntry->d_flags |= DCACHE_NEED_AUTOMOUNT;
+ spin_unlock(&direntry->d_lock);
+ }
+
return 1;
}
}
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